Atoms and Molecules

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Yes! Total mass of reactants = 5.3 + 6 = 11.3 g. Total mass of products = 2.2 + 0.9 + 8.2 = 11.3 g. Since mass before = mass after, this confirms the law of conservation of mass - matter cannot be cre

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Using the law of constant proportions, hydrogen and oxygen combine in a fixed 1:8 ratio. For 6 g hydrogen: 6 × 8 = 48 g of oxygen needed. This demonstrates that elements always combine in definite pro

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Atoms are incredibly small (radius ~10⁻¹⁰ m). Millions of atoms stacked together would barely equal the thickness of paper. They're smaller than the wavelength of visible light, so our eyes cannot det

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A chemical reaction occurs: CuSO₄ + Na₂CO₃ → CuCO₃ + Na₂SO₄. Blue copper sulphate changes to greenish copper carbonate precipitate. The flask is closed to prevent gas escape, ensuring total mass remai

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Step 1: Write symbols Ca and Cl. Step 2: Write valencies Ca²⁺ and Cl⁻. Step 3: Cross-multiply valencies. Step 4: Ca needs 2 Cl atoms to balance charges. Formula: CaCl₂. The 2+ charge of Ca is balanced

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This follows the Law of Constant Proportions (Law of Definite Proportions). Water molecules always have the formula H₂O - 2 hydrogen atoms (2×1=2u) and 1 oxygen atom (16u), giving a constant 2:16 = 1:

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1 atomic mass unit (u) = 1/12th the mass of one carbon-12 atom. Carbon-12 is chosen because: (1) it's stable, (2) it gives most elements whole number atomic masses, (3) carbon forms many compounds, ma

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Molecular mass = Sum of atomic masses of all atoms. H₂SO₄ contains: 2 H atoms (2×1=2u), 1 S atom (32u), 4 O atoms (4×16=64u). Total = 2+32+64 = 98u. This means one molecule of sulfuric acid is 98 time